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Aude Vernhet - One of the best experts on this subject based on the ideXlab platform.
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aggregation of a Proline Rich Protein induced by epigallocatechin gallate and condensed tannins effect of Protein glycosylation
Journal of Agricultural and Food Chemistry, 2008Co-Authors: Christine Pascal, Celine Poncetlegrand, Bernard Cabane, Aude VernhetAbstract:Astringency is one of the most important organoleptic qualities of numerous beverages, including red wines. It is generally thought to originate from interactions between tannins and salivary Proline-Rich Proteins (PRPs). In this work interactions between a glycosylated PRP, called II-1, and flavan-3-ols were studied in aqueous solutions and at a colloidal level, by dynamic light scattering (DLS) and small-angle X-ray scattering (SAXS). The flavan-3-ols were a monomer, epigallocatechin gallate (EGCG), and polymerized flavan-3-ol fractions extracted from grape seeds. In aqueous solutions containing EGCG and Protein II-1, Protein aggregation took place when Protein concentration and the EGCG/Protein ratio exceeded a threshold. The aggregates had a small size, comparable with the dimensions of Protein monomers, and formed stable dispersions (no phase separation). Most Proteins remained free in solution. This behavior is in sharp contrast with the phase separation observed for nonglycoslated PRP in the same c...
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interactions between a non glycosylated human Proline Rich Protein and flavan 3 ols are affected by Protein concentration and polyphenol Protein ratio
Journal of Agricultural and Food Chemistry, 2007Co-Authors: Christine Pascal, Celine Poncetlegrand, Anne Imberty, Catherine Gautier, Pascale Sarnimanchado, Ve Ronique A Cheynier, Aude VernhetAbstract:Interactions between salivary Proline-Rich Proteins and tannins are involved in astringency, which is one of the most important organoleptic sensations perceived when drinking wine or tea. This work aimed to study interactions between a recombinant human salivary Proline-Rich Protein, IB-5, and a flavan-3-ol monomer, epigallocatechin gallate (EGCG). IB-5 presented the characteristics of natively unfolded Proteins. Interactions were studied by dynamic light scattering, isothermal titration microcalorimetry, and circular dichroism. The interaction mechanism was dependent on Protein concentration. At low concentrations, a three-stage mechanism was evidenced. Saturation of the interaction sites (first stage) was followed by Protein aggregation into metastable colloids at higher EGCG/Protein ratios (second stage). Further increasing this ratio led to haze formation (third stage). At low ratios, a disorder-to-order transition of IB-5 structure upon binding was evidenced. At high Protein concentrations, direct b...
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Interactions between a non glycosylated human Proline-Rich Protein and flavan-3-ols are affected by Protein concentration and polyphenol/Protein ratio
Journal of Agricultural and Food Chemistry, 2007Co-Authors: Christine Pascal, Anne Imberty, Catherine Gautier, Ve Ronique A Cheynier, Celine Poncet-legrand, Pascale Manchado-sarni, Aude VernhetAbstract:Interactions between salivary Proline-Rich Proteins and tannins are involved in astringency, which is one of the most important organoleptic sensations perceived when drinking wine or tea. This work aimed to study interactions between a recombinant human salivary Proline-Rich Protein, IB-5, and a flavan-3-ol monomer, epigallocatechin gallate (EGCG). IB-5 presented the characteristics of natively unfolded Proteins. Interactions were studied by dynamic light scattering, isothermal titration microcalorimetry, and circular dichroism. The interaction mechanism was dependent on Protein concentration. At low concentrations, a three-stage mechanism was evidenced. Saturation of the interaction sites (first stage) was followed by Protein aggregation into metastable colloids at higher EGCG/Protein ratios (second stage). Further increasing this ratio led to haze formation (third stage). At low ratios, a disorder-to-order transition of IB-5 structure upon binding was evidenced. At high Protein concentrations, direct bridging between Proteins and EGCG was observed, resulting in significantly lower aggregation and turbidity thresholds
Christine Pascal - One of the best experts on this subject based on the ideXlab platform.
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Study of the interactions between a Proline-Rich Protein and a flavan-3-ol by NMR: residual structures in the natively unfolded Protein provides anchorage points for the ligands.
Biopolymers, 2009Co-Authors: Christine Pascal, Franck Paté, Véronique Cheynier, Marc-andré DelsucAbstract:Astringency is one of the major organoleptic properties of food and beverages that are made from plants, such as tea, chocolate, beer, or red wine. This sensation is thought to be due to interactions between tannins and salivary Proline-Rich Proteins, which are natively unfolded Proteins. A human salivary Proline-Rich Protein, namely IB-5, was produced by the recombinant method. Its interactions with a model tannin, epigallocatechin gallate (EGCG), the major flavan-3-ol in green tea, were studied here. Circular dichroism experiments showed that IB-5 presents residual structures (PPII helices) when the ionic strength is close to that in saliva. In the presence of these residual structures, IB-5 undergoes an increase in structural content upon binding to EGCG. NMR data corroborated the presence of preformed structural elements within the Protein prior to binding and a partial assignment was proposed, showing partial structuration. TOCSY experiments showed that amino acids that are involved in PPII helices are more likely to interact with EGCG than those in random coil regions, as if they were anchorage points for the ligand. The signal from IB-5 in the DOSY NMR spectrum revealed an increase in polydispersity upon addition of EGCG while the mean hydrodynamic radius remained unchanged. This strongly suggests the formation of IB-5/EGCG aggregates.
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aggregation of a Proline Rich Protein induced by epigallocatechin gallate and condensed tannins effect of Protein glycosylation
Journal of Agricultural and Food Chemistry, 2008Co-Authors: Christine Pascal, Celine Poncetlegrand, Bernard Cabane, Aude VernhetAbstract:Astringency is one of the most important organoleptic qualities of numerous beverages, including red wines. It is generally thought to originate from interactions between tannins and salivary Proline-Rich Proteins (PRPs). In this work interactions between a glycosylated PRP, called II-1, and flavan-3-ols were studied in aqueous solutions and at a colloidal level, by dynamic light scattering (DLS) and small-angle X-ray scattering (SAXS). The flavan-3-ols were a monomer, epigallocatechin gallate (EGCG), and polymerized flavan-3-ol fractions extracted from grape seeds. In aqueous solutions containing EGCG and Protein II-1, Protein aggregation took place when Protein concentration and the EGCG/Protein ratio exceeded a threshold. The aggregates had a small size, comparable with the dimensions of Protein monomers, and formed stable dispersions (no phase separation). Most Proteins remained free in solution. This behavior is in sharp contrast with the phase separation observed for nonglycoslated PRP in the same c...
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interactions between a non glycosylated human Proline Rich Protein and flavan 3 ols are affected by Protein concentration and polyphenol Protein ratio
Journal of Agricultural and Food Chemistry, 2007Co-Authors: Christine Pascal, Celine Poncetlegrand, Anne Imberty, Catherine Gautier, Pascale Sarnimanchado, Ve Ronique A Cheynier, Aude VernhetAbstract:Interactions between salivary Proline-Rich Proteins and tannins are involved in astringency, which is one of the most important organoleptic sensations perceived when drinking wine or tea. This work aimed to study interactions between a recombinant human salivary Proline-Rich Protein, IB-5, and a flavan-3-ol monomer, epigallocatechin gallate (EGCG). IB-5 presented the characteristics of natively unfolded Proteins. Interactions were studied by dynamic light scattering, isothermal titration microcalorimetry, and circular dichroism. The interaction mechanism was dependent on Protein concentration. At low concentrations, a three-stage mechanism was evidenced. Saturation of the interaction sites (first stage) was followed by Protein aggregation into metastable colloids at higher EGCG/Protein ratios (second stage). Further increasing this ratio led to haze formation (third stage). At low ratios, a disorder-to-order transition of IB-5 structure upon binding was evidenced. At high Protein concentrations, direct b...
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Interactions between a non glycosylated human Proline-Rich Protein and flavan-3-ols are affected by Protein concentration and polyphenol/Protein ratio
Journal of Agricultural and Food Chemistry, 2007Co-Authors: Christine Pascal, Anne Imberty, Catherine Gautier, Ve Ronique A Cheynier, Celine Poncet-legrand, Pascale Manchado-sarni, Aude VernhetAbstract:Interactions between salivary Proline-Rich Proteins and tannins are involved in astringency, which is one of the most important organoleptic sensations perceived when drinking wine or tea. This work aimed to study interactions between a recombinant human salivary Proline-Rich Protein, IB-5, and a flavan-3-ol monomer, epigallocatechin gallate (EGCG). IB-5 presented the characteristics of natively unfolded Proteins. Interactions were studied by dynamic light scattering, isothermal titration microcalorimetry, and circular dichroism. The interaction mechanism was dependent on Protein concentration. At low concentrations, a three-stage mechanism was evidenced. Saturation of the interaction sites (first stage) was followed by Protein aggregation into metastable colloids at higher EGCG/Protein ratios (second stage). Further increasing this ratio led to haze formation (third stage). At low ratios, a disorder-to-order transition of IB-5 structure upon binding was evidenced. At high Protein concentrations, direct bridging between Proteins and EGCG was observed, resulting in significantly lower aggregation and turbidity thresholds
Ranjan Swarup - One of the best experts on this subject based on the ideXlab platform.
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formation of the stomatal outer cuticular ledge requires a guard cell wall Proline Rich Protein
Plant Physiology, 2017Co-Authors: Lee Hunt, Sam Amsbury, Alice L Baillie, Mahsa Movahedi, Alice Mitchell, Mana Afsharinafar, Kamal Swarup, Thomas Denyer, Jamie K Hobbs, Ranjan SwarupAbstract:Stomata are formed by a pair of guard cells which have thickened, elastic cell walls to withstand the large increases in turgor pressure that have to be generated to open the pore that they surround. We have characterised FOCL1, a guard cell-expressed, secreted Protein with homology to hydroxyProline-Rich cell wall Proteins. FOCL1-GFP localises to the guard cell outer cuticular ledge and plants lacking FOCL1 produce stomata without a cuticular ledge. Instead the majority of stomatal pores are entirely covered-over by a continuous fusion of the cuticle, and consequently plants have decreased levels of transpiration and display drought tolerance. The focl1 guard cells are larger and less able to reduce the aperture of their stomatal pore in response to closure signals suggesting that the flexibility of guard cell walls is impaired. FOCL1 is also expressed in lateral root initials where it aids lateral root emergence. We propose that FOCL1 acts in these highly specialised cells of the stomata and root to impart cell wall strength at high turgor and/or to facilitate interactions between the cell wall and the cuticle.
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formation of the stomatal outer cuticular ledge requires a guard cell wall Proline Rich Protein
Plant Physiology, 2017Co-Authors: Lee Hunt, Sam Amsbury, Alice L Baillie, Mahsa Movahedi, Alice Mitchell, Mana Afsharinafar, Kamal Swarup, Thomas Denyer, Jamie K Hobbs, Ranjan SwarupAbstract:Stomata are formed by a pair of guard cells which have thickened, elastic cell walls to withstand the large increases in turgor pressure that have to be generated to open the pore that they surround. We have characterized FOCL1, a guard cell-expressed, secreted Protein with homology to Hyp-Rich cell wall Proteins. FOCL1-GFP localizes to the guard cell outer cuticular ledge and plants lacking FOCL1 produce stomata without a cuticular ledge. Instead the majority of stomatal pores are entirely covered over by a continuous fusion of the cuticle, and consequently plants have decreased levels of transpiration and display drought tolerance. The focl1 guard cells are larger and less able to reduce the aperture of their stomatal pore in response to closure signals suggesting that the flexibility of guard cell walls is impaired. FOCL1 is also expressed in lateral root initials where it aids lateral root emergence. We propose that FOCL1 acts in these highly specialized cells of the stomata and root to impart cell wall strength at high turgor and/or to facilitate interactions between the cell wall and the cuticle.
Tatiana Efimova - One of the best experts on this subject based on the ideXlab platform.
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Delayed skin wound repair in Proline-Rich Protein tyrosine kinase 2 knockout mice
American journal of physiology. Cell physiology, 2014Co-Authors: Aaron C. Koppel, Alexi Kiss, Anna Hindes, Carole J. Burns, Barry L. Marmer, Gregory I. Goldberg, Miroslav Blumenberg, Tatiana EfimovaAbstract:Proline-Rich Protein tyrosine kinase 2 (Pyk2) is a member of the focal adhesion kinase family. We used Pyk2 knockout (Pyk2-KO) mice to study the role of Pyk2 in cutaneous wound repair. We report th...
Irene Messana - One of the best experts on this subject based on the ideXlab platform.
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the intriguing heterogeneity of human salivary Proline Rich Proteins short title salivary Proline Rich Protein species
Journal of Proteomics, 2016Co-Authors: Barbara Manconi, Tiziana Cabras, Massimo Castagnola, Alessandra Olianas, Alberto Vitali, Claudia Desiderio, Maria Teresa Sanna, Irene MessanaAbstract:The most heterogeneous family of human salivary Proteins is represented by Proline-Rich Proteins (PRPs) divided in acidic, basic, and basic glycosylated (aPRPs, bPRPs, gPRPs). They are encoded by six genes, clustered on chromosome 12p13.2: PRH1-2 encode aPRPs, PRB1-4 encode bPRPs and gPRPs. Each gene exists in different allelic forms: two for PRH2, three for PRH1, PRB2, and PRB4, four for PRB1, and PRB3. During granule maturation, PRP proProteins undergo proteolysis by the action of convertases and carboxypeptidases. Differently from bPRPs, proteolysis of aPRPs is not complete, and, besides fragments, entire Protein species are also secreted. Maturation process generates ten aPRPs (PRP-1, PRP-2, PIF-s, Db-s, Pa, PRP-3, PRP-4, PIF-f, Db-f, P-C), and at least 18 bPRPs (II-2, P-E, IB-6, Ps-1, Ps-2, IB-1, P-J, IB-8a, P-F, P-H, P-D, II-1, Protein glycosylated A, CD-IIg, and Gl1-4). In addition, single nucleotide and length polymorphisms, and differentially spliced transcripts originate several natural variants. Phosphorylation, N-pyroglutaminylation, dimerization, and N-/O-glycosylation also occur during maturation, enlarging the number of Protein species, further increased by proteolytic events governed by carboxy- and endo-peptidases during and after secretion, and giving rise to a huge number of small peptides. The PRP functional role is still poorly understood.The high polymorphism of PRPs gives an important contribution to the high heterogeneity and inter-individual variability of the human salivary proteome. The products of six genes clustered on chromosome 12p13.2 comprise a mixture of entire, truncated, phosphorylated, glycosylated and dimerized Protein/peptide species, sharing large part of their sequences, and possibly involved in different biological activities. Whatever the role of PRP species is, it should be crucial, given that PRPs are the most conserved oral salivary Proteins among mammals.
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characterization of the human salivary basic Proline Rich Protein complex by a proteomic approach
Journal of Proteome Research, 2004Co-Authors: Irene Messana, Tiziana Cabras, Rosanna Inzitari, Alessandro Lupi, Cecilia Zuppi, Chiara Olmi, Maria Benedetta Fadda, Massimo Cordaro, Bruno Giardina, Massimo CastagnolaAbstract:Thirteen samples of human normal whole saliva were analyzed by RP-HPLC−ESI−MS and MALDI-TOF−MS to investigate the basic Proline-Rich Protein complex. Between known basic-PRPs the P-B, P-C (or IB-8b), P-D (or IB-5), P-E (or IB-9), P-F (or IB-8c), P-H (or IB-4), IB-6, II-2, IB-1, and IB-8a glucosylated were identified, whereas the II-1, IB-7, PA, and D1-A peptides were not detected. Some detected masses not attributable to known basic-PRPs were putatively ascribed to II-2 and IB-1 nonphosphorylated, II-2 and IB-1 missing the C-terminal arginine residue, and the 1-62 fragment of IB-6, named P-J peptide. A correlation matrix analysis revealed a cluster of correlation among all the basic PRPs (apart from the P-B peptide) which is in agreement with their common parotid origin. Keywords: basic Proline-Rich Proteins • human • saliva • mass spectrometry
